ArcB: El sensor del estado redox en bacterias

The Arc two-component system comprises the sensor kinase ArcB and the response regulator ArcA. In Escherichia coli, this system regulates the transcriptional network involved in energy metabolism according to the redox conditions of their environment. Under anoxic growth conditions, ArcB autophosphorylates and transphosphorylates ArcA, which in turn represses or activates the expression of its target operons. Under aerobic conditions, ArcB acts as a phosphatase that catalyzes the dephosphorylation of ArcA-P and thereby releasing its transcriptional regulation. This review describes the key structural features of ArcB, and the main events for Arc signaling, including signal reception and kinase regulation. It also compares the ArcB sequence of E. coli with the one of other bacteria and reveals similarities and differences that may be of foremost importance for the regulation of this sensor kinase protein.